1. Field of the Invention
This invention relates to an information recording method and, more particularly, to an information recording apparatus, information recording/reproducing apparatus, information recording method and information reproducing method in which a recording medium used has an erasure unit larger than a writing unit.
2. Description of the Related Art
In the U.S. Pat. No. 5,619,570 and U.S. Ser. No. 08/338,538, the present Assignee has proposed an device in which a variety of information items can be purveyed by transferring the information such as speech, pictures, letters or programs from an information purveying device (information transferring device) to a recording device or a recording/reproducing device.
FIG. 1 shows a perspective view of a conventional first information recording/reproducing device 200A proposed in the above publications. The information recording/reproducing device 200A includes a coupling terminal 201, a display 202, a function selection section 203 and a recording medium, not shown, in the inside of the device.
The information recording/reproducing device 200A records the information purveyed by an information purveying device, not shown, via coupling terminal 201. There is no limitation to the contents of the information purveyed by the information purveying device which may be text information, speech information, picture information or computer programs. There is also no limitation to the types of the recording medium. However, semiconductor memories, capable of high-speed copying and random accessing and exhibiting superior portability, may preferably be employed.
The information recording/reproducing device 200A displays the contents of the information recorded on the recording medium on the display 202. The function selection section 203 is made up of, for example, pushbutton switches. The user selects the information recorded on the recording medium using the function selection section 203 for reproducing the desired information.
If the information recorded on the recording medium is a computer program, information reproduction means executes the program. In such case, the user can enter the information during execution, if need be. If the information recorded on the recording medium is the textual or picture information, it is displayed on the display 202 constituted by, for example, a liquid crystal display device. If the information is the speech information, it is outputted to an earphone 204. The earphone 204 may also be replaced by a speaker, or an output terminal for playback signals may be provided on the information recording/reproducing device 200A for connection to an external display device or a speaker.
FIG. 2 shows a perspective view showing a second conventional information recording/reproducing device 200B proposed in the above publication. The information recording/reproducing device 200B, made up of an information recording device 210 and an information reproducing device 220, is such a device in which the function of recording the information and that of reproducing the recorded information of the first information recording/reproducing device 200A are separated from each other.
In the information recording/reproducing device 200B, the information recording device 210 is inserted into an inserting/ejecting port 221 of the information reproducing device 220, for reproducing the information recorded on the information recording device 210. For reproducing the information recorded on the information recording device 210 by the information reproducing device 220, it becomes necessary to transmit data and information items between the information recording device 210 and the information reproducing device 220. The information recording device 210 is configured so that a coupling terminal 212 is provided for coupling to the information reproducing device 220 and a coupling terminal, not shown, associated with the coupling terminal 212, is provided in the information reproducing device 220, with the two coupling terminals being coupled together on loading the information recording device 210 on the information reproducing device 220. Although the information recording device 210 includes two coupling terminals, namely the coupling terminal 211 for coupling to the information purveying device as later explained and the coupling terminal 212 for coupling to the information reproducing device 220, a sole terminal may be used in place of the two terminals for switching between the two devices.
The information recording device 210 may be constituted solely by a recording medium, whereby the information recording device is a portable information recording device smaller in size and lighter in weight. In such case, readout from the recording medium or writing in the recording medium is controlled on the side of the information reproducing device 220 or the information purveying device.
FIG. 3 shows a perspective view of a conventional first information purveying device 230 proposed in the above-referenced Publication. The information purveying device 230 includes a display 231 for displaying the contents or costs of the purveyed information, an output selection section 232 for selecting the information desired by the user and an insertion/ejection port 230 via which the user can insert the information purveying device 230 into the information recording/reproducing device for recording the information. The information purveying device 230 also includes a recording medium having stored therein the information purveyed to the device and an information copying controller for writing the information in the information recording/reproducing device.
The user connects the coupling terminal 201 of the information recording/reproducing device 200A shown in FIG. 1 to a coupling terminal, not shown, provided in the information purveying device 230. The user also inserts the information recording device 210 shown in FIG. 2 in the insertion/ejection port 233 of the information purveying device 230. The user selects the information desired to be purveyed by the output selection section 232 based on the contents and costs of the information displayed on the display 231. The information copying controller of the information purveying device 230 writes the information purveying the selected information in the information recording/reproducing device 200A or in the information recording device 210.
Meanwhile, the information purveying device 230 need not be provided with the recording medium having the purveyed information recorded thereon. Instead, the information purveying device 230 may be connected to an information purveying center over wired or wireless communication means so that the desired information will be purveyed to the user via this communication means. If the recording medium is provided in the information purveying device 230, it is possible to update the information stored in the recording medium by the communication means for purveying the latest information while suppressing the communication cost.
FIG. 4 shows a perspective view of a second information purveying device 240 as proposed in the above-referenced publication. The information purveying device 240 is a device for purveying the information to the information recording device 210 shown in FIG. 2 and is configured so that an insertion port 241 and an ejection port 242 of the information recording device 210 are spaced apart at a distance from each other. This information purveying device 240 includes movement means, not shown, for transporting the information recording device 210 inserted into the insertion port 241. After copying the information to be purveyed, the information purveying device 240 ejects the information recording device 210 inserted into the insertion port 241 at the ejection port 242. A person desirous to have the information H receives the copy of the information as he or she walks in a direction of arrow A. The information purveying device 240 can purvey the information promptly to plural persons.
The conventional writing method in case the information is written from the information purveying device to the information recording/reproducing device and the recording medium provided in the information recording/reproducing device is such a recording medium in which the data erasure range is larger than the writing range as in a flash memory is now explained.
In a recording medium in which an erasure operation needs to be carried out before executing the data writing operation, such as one used in the flash memory, the erasure unit, referred to herein as a block, is usually larger than the writing unit, referred to herein as a page. Therefore, if the recorded data is erased before proceeding to data writing, there are occasions wherein data to be erased and data not to be erased exist together in a block. In such case, the data contained in the block for erasure and that is not to be erased is transiently retreated to, for example, a buffer provided outside the recording medium, and again written after the end of the erasure of all data in the block. This lowers the writing efficiency. Moreover, with this method, an external buffer is needed for storing one-block data.
Referring to a memory map diagram of FIG. 5, a method for writing data recorded in the flash memory as a recording medium is explained. A recording medium 103 uses three units of C (Chip), B(Block) and P(page) as a method for displaying the physical addresses. It is noted that C, B and P denote the number c of a recording medium chip or memory chip, the number b of a bloc k as the smallest section of erasure and the number p of the page as the smallest writing unit. The physical address of the memory chip 103 is represented as CBP [c:b:p] in association with CBP. The page capacity is 512 bytes in association with a file allocation table (FAT) filing system.
As a method for identifying data recorded on the recording medium 103, two units of F (file) and S (sector) are used, where F is the number of a file and S is the number s of the sector constituting the file. The data identification method is represented by FS[f:s] in association with f and s. It is noted that FS shown in the recording medium 103 is the identification number associated with the actually recorded sector data and FS shown in the file manager 104 records the identification number itself.
The recording medium 103 is made up of a sole memory chip. This memory chip C[0] is made up of four blocks of from block B[0] to B[3].
All data recorded on the recording medium 103 are managed by a file management section 104 in which there are recorded the leading physical address CBP[c:b:p] and the last sector number FS[f:s] in each file. The file management section 104 records the file management information in the logical addresses M[0] to M[I0-1], where m denotes the maximum number of files that can be managed by the file management section 104.
Referring to FIG. 5, the contents recorded in the recording medium 103 managed by the file management section 104 are as follows: There are recorded in the recording medium 103 two records, the logical sequence of which is F[1], F[0]. The file F[1] is recorded with the capacity of 6 sectors from address CBP [0:0:3], while the file F[0] is recorded with the capacity of 3 sectors from address CBP [0:0:0], with the file F[0] and the file F[1] being recorded across three blocks. Since there is only one memory chip C[0] in the present instance, it is possible to omit C[0] as the file management information and the physical address.
It is assumed, for explanation sake, that the file F[0] of the recording medium 103, where the above-mentioned file F[0] and the file F[1] have been recorded, is rewritten. Since the data FS[1:0] of the file F[1] is contained in the block B[0], data FS[1:0] contained in the block B[0] and that is not to be erased is retreated to an external buffer. The block B[0] is then erased. A new file F[0] is then written, along with retreated data FS[1:0], in the block B[0].
Therefore, as an operation other than actual writing operation, retreating of required data, block erasure or rewriting of retreated data are required. These operations represent an overhead in the writing operation, thus lowering the writing efficiency.
Another method for preventing the lowering of the writing efficiency is background erasure. This background erasure is, writing a new file in an address of a previously erased separate area in place of erasing the old file for writing a new file in the same address. After the end of the writing of the new file, an old file is erased during the system idle time. This apparently realizes high-speed writing.
In this background erasure, it is assumed, for explanation sake, that the file F[1], recorded on the recording medium 103 along with the file F[0], as shown in FIG. 5, is rewritten to file F[2].
In rewriting the file F[1], the new file F[2] is written in the 6-sector area from address CBP[0:2:1] already erased. Simultaneously, the file management information in the file management section 104 is changed. Subsequently, during the time the writing or readout for the recording medium 103 is not going on, the block B[1] that constituted the old file F[1] is erased.
FIG. 6 is a memory map diagram showing the results of background erasing of the file F[1] of the recording medium 103 shown in FIG. 5 for rewriting to the file F[2]. It is only four sectors of data FS[1:1] to FS[1:4] making up a block that can be erased by background erasure. Thus, data FS[1:0] of file F[1] and data FS[1:5] are left without erasure in the block B[0] and in the block B[2], respectively.
Meanwhile, if there is no sufficient vacant apace in the recording medium 103 for recording a new file, it is difficult to write data at a high speed by background erasure.
In the recording medium 103 in the state shown in FIG. 7, there are recorded three files, the logical sequence of which is F[1], F[2] and F[0]. These files F[1], F[2] and F[0] are recorded with the capacity of 6 sectors from the address CBP [0:0:3], the capacity of 4 sectors from the address CBP[0:2:1] and with the capacity of 3 sectors from the address CBP [0:0:0], respectively, such that the file F[0], file F[1] and file F[2] exist across four blocks.
In the instance shown in FIG. 7, it is impossible to rewrite the file F[1] with 6 sectors by the above-mentioned background erasure. For such rewriting, the old file needs to be erased first of all. Since the file F[1] is recorded across the blocks B[0] to B[2], these blocks need to be erased first. However, another file F[0] and part of the file F[2] are also recorded in this area. Thus it becomes necessary to have the file F[0] and part of the file F[2] transiently retreated in, for example, an external buffer before erasure and to rewrite the file F[0] and part of the file F[2] in the recording medium after end of the erasure.
That is, since the data in the block under erasure is made up of necessary data, that is data that should not be erased, and unneeded data, that is data that can be erased, it is necessary to effect a data retreating operation with the aid of the external buffer.
Thus, as compared to a recording medium capable of data overwriting, significant overhead occurs at the time of writing, thus increasing the sum of write time.
This inconvenience is enhanced if the recording medium is constituted by plural memory chips and the files to be erased are recorded across plural memory chips. That is, in recording across plural memory chips, since recorded sector data making up a file are distributed in plural memory chips, it is necessary to check whether or not part of other files co-exists in all blocks making up a file. If the result is affirmative, it becomes necessary to perform the above-mentioned retreating operation and re-writing operation.
This situation occurs frequently if the musical numbers each of approximately three minutes are recorded on a recording medium capable of recording 10 minutes of music, and one of these three musical numbers is to be replaced by a new musical number, that is if the proportion of a file is large as compared to the capacity of the recording medium.
On the other hand, high-speed read-out performance is desirable for file read-out for coping with diversified application. However, since the power consumption is increased by the high-speed operation, an inconvenience is raised in connection with application for portable equipment.